msm: iommu: Synchronize access to IOMMU cfg port

Add remote spinlock that allows CPU and GPU to
synchronize access to IOMMU hardware.

Add usage of remote spinlock to iommu driver and
add depenency on SFPB hardware mutex being enabled.`

This feature is not using SFPB hardware mutex. However,
SFPB hardware mutex must be enabled since the remote
spinlock implementation is making use of shared memory
that is normally used when SFPB hardware mutex is not enabled.

Change-Id: I42e11d742e295110843c4b45d6d27cc665d42b7b
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Alex Wong <waiw@codeaurora.org>